Angioplasty balloon catheters and their methods of use are well known. For example, U.S. Pat. No. 5,035,686 to Crittenden and U.S. Pat. No. 4,976,689 to Buchbinder et al. provide general descriptions of angioplasty balloon catheters and their methods of use. The contents of these patents are incorporated herein by reference. Typically, an angioplasty balloon catheter is positioned at a lesion or stenosis in a blood vessel by locating a guide wire at the proper position and then pushing the catheter over the wire. Such a system is commonly referred to as an "over-the-wire" system. The over-the-wire system is desirable because it is relatively easy to push the catheter along the wire to the proper location. However, the over-the-wire system has several drawbacks.
The over-the-wire system does not protect the patient in the event that the balloon ruptures. Should the balloon rupture, pieces of the balloon or the liquid used to inflate the balloon may injure the patient. The over-the-wire system exposes both the catheter and the guide wire to the patient's blood and body fluid thus making reuse of the relatively expensive balloon catheter and wire impractical because of the prohibitive time and cost of re-sterilizing the contaminated instruments. The over-the-wire system does not allow the surgeon to ascertain whether or not the lesion can be penetrated by the balloon until after the costly sterile tray has been opened, sometimes resulting in unnecessary expense. The over-the-wire system does not allow for the rapid exchange of catheters or wires should the surgeon find that a different size or stiffness is required. Also, the over-the-wire system typically requires the guide wire to remain in place during the procedure. The wire must be withdrawn for the surgeon to fluoroscopically "see" the lesion or stenosis. Moreover, such exchanges or withdrawals may be injurious to the patient because of the increased possibility that the patient's artery will be perforated or damaged by repeatedly inserting and removing instruments that directly contact the blood vessel. Damage to the blood vessel walls may result in a thrombus formation, or clot, which is dangerous or even fatal to the patient.
Certain angioplasty balloon catheter systems provide for an exchange of guide wires and balloon catheters. Such exchanges typically require additional instruments such as a wire extension or wire restraining system which requires two persons to operate. Also, catheters are typically manufactured to accommodate only a particular manufacturer's wire, thus sometimes making an exchange impossible if that manufacturer does not make a particular wire or if one is not on hand. These exchanges are often time consuming, an undesirable characteristic of any surgical instrument. Also, the prior art rapid exchange devices have eccentrically located guide wires, thus having inferior control and pushability.
U.S. Pat. No. 5,201,756 to Horzewski et al. discloses a catheter sheath made of a radially expandable material. This sheath is an over-the-wire device which may accommodate a variety of different sized catheters. It does not overcome the problems of the prior art. U.S. Pat. No. 5,219,335 to Willard et al. discloses an over-the-wire introducer sheath and a balloon catheter. The balloon catheter has perfusion openings which allow blood to flow distally of the catheter, but also exposes the catheter to the patient's blood.
U.S. Pat. Nos. 4,976,689 to Buchbinder et al., and 4,327,709 to Hansen et al. disclose sheaths for balloon catheters. However, neither sheath protects the patient from balloon rupture, nor prevents the catheter and wire from contamination, nor prevents damage to the artery walls due to wire and/or catheter exchanges. The sheath of the Buchbinder et al. patent may also operate as a perfusion device, but permits the patient's blood and other bodily fluids to contaminate the catheter and guide wire.
U.S. Pat. No. 4,646,722 to Silverstein et al. discloses a protective sheath for an endoscope allowing for the reuse of the scope. This sheath does not allow for the rapid exchange of catheters or wires, does not allow for the inflation of a balloon catheter, and must be pre-loaded on the scope before use.
It would therefore be desirable to provide a system which would overcome the drawbacks of these prior art systems.